The impacts of elevated temperature and moderate hypoxia on the production characteristics, cardiac morphology and haematology of Atlantic salmon (Salmo salar)

Ajiboye, Olufemi (2019) The impacts of elevated temperature and moderate hypoxia on the production characteristics, cardiac morphology and haematology of Atlantic salmon (Salmo salar). Masters thesis, Memorial University of Newfoundland.

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Abstract

Salmon in sea cages are exposed to high water temperatures and low dissolved oxygen levels (i.e., hypoxia) that are predicted to worsen with climate change. I examined the impacts of an incremental temperature increase (1⁰C/week to 20⁰C or 23⁰C) and moderate hypoxia (~70% air saturation) on the production characteristics, cardiac morphometrics and haematology of farmed Atlantic salmon (Salmo salar) of Saint John River origin under laboratory conditions. While temperatures up to 20⁰C had few negative effects on the salmon, hypoxia significantly reduced feed consumption and growth, and further temperature increases adversely affected the fish. Specific growth rate and feed consumption dropped dramatically after 20⁰C, and mortalities began at 21⁰C and reached ~ 30% by 23⁰C. Salmon exposed to high temperature alone had increased relative ventricular mass (by 21%), whereas those exposed to high temperature and hypoxia had a 15% greater blood oxygen carrying capacity. This research suggests that further increases in coastal ocean temperatures may negatively affect farmed salmon production, especially if combined with hypoxia.

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